1. Field of the Invention
This invention relates to a method of producing spherical-shaped particles of copolymers and one or more coating additives and/or crosslinkers, the particles being useful for coating substrates; and to the particles themselves.
2. State of the Art
This invention is an improvement in the process described in U.S. Pat. Nos. 4,056,653 and 3,933,954. The improvement comprises forming substantially spherical particles that contain the coating copolymer and other additives typically employed in coatings of such copolymer. The problem solved by the improved process is how to produce spherical particles having varied components, in addition to copolymer, from a broader range of copolymers than suggested by the cited patents. Application of such particles to a substrate (for instance, in a fluidized bed) produces coatings ready to be crosslinked by art--recognized means into durable, aesthetically pleasing surfaces resistant to chemical attack and delamination. Heretofore, spherical particles such as described have not been known. Careful selection of particle components and the time/temperature profile employed during particle formation insures ready application of all necessary coating components to the substrate from the spherical particle matrix containing them, in a single fluidized bed immersion step.